The boys had once been friends before MS-13 began recruiting one of them. Now, as other students streamed to class one April morning at William Wirt Middle School in Riverdale, Md., the two teens squared off in the third-story bathroom — a fight captured by another student on his cellphone.

The MS-13 recruit threw a punch at his former friend’s head. His opponent ducked and tackled the 15-year-old, their sneakers squealing as they tumbled to the green tile floor.

“I like that,” someone shouted off-camera as the recruit tried to cover his head.

“That look like it hurt,” someone wrote under the video, which was uploaded to Instagram on April 19 and has been viewed more than 400 times.

Gang-related fights are now a near-daily occurrence at Wirt, where a small group of suspected MS-13 members at the overwhelmingly Hispanic school throw gang signs, sell drugs, draw gang graffiti and aggressively recruit students recently arrived from Central America, according to more than two dozen teachers, parents and students. Most of those interviewed asked not to be identified for fear of losing their jobs or being targeted by MS-13.